It is known that when an object is imaged on the image sensing surface of an image sensor via an optical system including a zoom lens, the image sensed by the image sensor blurs under the influence of aberration of the optical system, unlike the original object, degrading the image quality.
It is known that when an object is imaged onto the image sensing surface of an image sensor via an optical system where its focal plane is placed on an offset position from a position of an object to be imaged, the image captured by the image sensor gets blurred. Thus, the image quality of the captured image is degraded.
A technique for preventing the degradation of image quality is deconvolution. This technique generates an unblurred clear sensed image by detecting a blur state from one sensed image containing a blur. Deconvolution, which is reverse to convolution, obtains an input function from an output function and weight function.
A coded aperture technique particularly enables deconvolution with different blur functions. For this purpose, the stop, which greatly affects the blur state, is set to a special shape, and an index for detecting a blur state is embedded in a sensed image.
According to a technique described in non-patent reference 1, a blur generated in an image sensed via a special fixed stop is embedded in a sensed image as the index for detecting a blur state. A blur function produced in the sensed image has a wide characteristic frequency distribution, and allows detecting a blur state which changes depending on the depth of each portion of an object.
According to a technique described in non-patent reference 2, a blur generated using a special stop is similarly embedded in a sensed image as the index for detecting a blur state. This technique intentionally reduces a specific frequency component in the blur function to detect a blur state which changes depending on the depth of each portion of an object.
[Non-patent Reference 1] Veeraraghavan, Raskar, R., Agrawal, A., Tumblin, J. (2007), “Dappled Photography: Mask Enhanced Cameras for Heterodyned Light Fields and Coded Aperture Refocusing”, ACM Transactions on Graphics (Proc. SIGGRAPH)
[Non-patent Reference 2] Levin, A., Fergus, R., Durand, F., Freeman, B. (2007), “Image and Depth from a Conventional Camera with a Coded Aperture”, ACM Transactions on Graphics (Proc. SIGGRAPH)
However, the techniques in non-patent references 1 and 2 employ a stop of a fixed shape. This limits a method for embedding the index in a sensed image to detect a blur state.